Athabasca ARK RGND(Reverse GND filter),it is normally used for less light scenes like sunrise and sunset.
Athabasca ARK RGND filter uses German Schott optical glass, with multi-ultrathin noble metal coating, it has the advantage of low reflection, and low color deviation. Also it adopts double-layer water repellent coating, it is really water repellent, scratch and stain resistant.